Louis Peyton commits the first murder on the Moon, and eccentric extraterrologist Wendell Urth is consulted to help prove he did it.

This is the first Wendell Urth story, and not the best although good enough to justify the series. Urth himself resembles some of Asimov’s other eccentric scientists, such as Computer Twissel in The End of Eternity, but is a far more interesting armchair detective than some of Asimov’s later creations. Here we don’t have a whodunit or howdunit or anything-dunit, but a hows-he-gonna-get-caught, and Urth does it in what (to me) at least seems a plausible fashion, although, according to the afterword in Asimov’s Mysteries, at least one fan performed an experiment which seemed to indicate that Urth’s solution would not, in fact, work.